﻿PROF. 
  C. 
  LAPWOETH 
  ON 
  THE 
  GIEVAK 
  SUCCESSION. 
  631 
  

  

  whapple 
  beds, 
  as 
  he 
  will 
  recognize 
  amongst 
  them 
  some 
  of 
  the 
  most 
  

   peculiar 
  and 
  characteristic 
  Glenshalloch 
  forms. 
  

  

  Hence, 
  if 
  no 
  unconformability 
  intervenes 
  to 
  cause 
  a 
  strati- 
  

   graphical 
  break 
  in 
  the 
  succession 
  we 
  have 
  already 
  developed 
  (and, 
  

   as 
  we 
  have 
  seen, 
  there 
  appears 
  to 
  be 
  no 
  evidence 
  in 
  the 
  northern 
  

   inlier 
  in 
  favour 
  of 
  such 
  a 
  break), 
  it 
  is 
  clear 
  at 
  the 
  outset 
  that 
  

   between 
  these 
  Graptolite-bearing 
  shales 
  of 
  Penwhapple 
  and 
  the 
  

   Barren 
  Flagstones, 
  with 
  which 
  the 
  Saugh-Hill 
  fault 
  has 
  placed 
  them 
  

   in 
  physical 
  contact 
  to 
  the 
  south, 
  there 
  are 
  actually 
  missing 
  the 
  

   entire 
  subformations 
  of 
  the 
  DrummucJc 
  Mudstones 
  and 
  the 
  Mulloch- 
  

   Hill 
  Sandstones, 
  a 
  vertical 
  extent 
  of 
  rock 
  at 
  least 
  600 
  feet 
  in 
  

   collective 
  thickness. 
  

  

  A 
  more 
  extended 
  examination 
  of 
  these 
  Graptolitic 
  flagstones 
  and 
  

   grits, 
  as 
  here 
  exhibited, 
  while 
  it 
  will 
  finally 
  fix 
  in 
  the 
  mind 
  of 
  the 
  

   investigator 
  the 
  conviction 
  of 
  their 
  general 
  identity 
  with 
  the 
  

   similar 
  Glenshalloch 
  series, 
  will 
  have 
  the 
  further 
  result 
  of 
  showing 
  

   him 
  that 
  some 
  of 
  the 
  most 
  conspicuous 
  zones 
  of 
  rock 
  apparent 
  in 
  

   that 
  area 
  are 
  missing 
  from 
  this 
  Penwhapple 
  section, 
  while 
  other 
  

   bands 
  are 
  here 
  very 
  conspicuous, 
  which 
  are 
  apparently 
  wanting 
  in 
  

   the 
  Newlands 
  and 
  Glenshalloch 
  area. 
  

  

  We 
  have 
  shown 
  that, 
  in 
  spite 
  of 
  the 
  innumerable 
  inversions 
  

   and 
  dislocations 
  determinable 
  among 
  the 
  Ardmillan 
  strata 
  of 
  the 
  

   higher 
  parts 
  of 
  Penwhapple 
  Glen, 
  there 
  is 
  nevertheless 
  a 
  generally 
  

   ascending 
  succession 
  as 
  we 
  pass 
  over 
  the 
  edges 
  of 
  the 
  strata 
  from 
  

   south 
  to 
  north. 
  As 
  the 
  strata 
  now 
  under 
  examination 
  are 
  similarly 
  

   affected 
  by 
  physical 
  accidents, 
  there 
  is 
  a 
  strong 
  a 
  'priori 
  probability, 
  

   amounting 
  almost 
  to 
  certainty, 
  that 
  they 
  will 
  be 
  found 
  to 
  be 
  subject 
  

   to 
  the 
  same 
  general 
  rule. 
  We 
  shall, 
  indeed, 
  show 
  in 
  the 
  sequel 
  

   that 
  even 
  the 
  regularly 
  disposed 
  rock-bands 
  on 
  the 
  northern 
  side 
  of 
  

   the 
  datum-line 
  of 
  the 
  Camregan 
  Pentamerus 
  -limestone 
  follow 
  pre- 
  

   cisely 
  the 
  same 
  rule 
  of 
  inverted 
  succession. 
  

  

  Starting, 
  therefore, 
  from 
  the 
  line 
  of 
  the 
  Saugh-Hill 
  fault, 
  let 
  us 
  

   study 
  the 
  Penwhapple 
  section 
  in 
  detail, 
  regarding 
  the 
  visible 
  strata 
  

   as 
  inverted 
  in 
  position, 
  and 
  treating 
  of 
  the 
  whole 
  as 
  a 
  generally 
  

   ascending 
  sequence 
  (fig. 
  24). 
  

  

  (Cba) 
  Diployraptus-modestus 
  Shales. 
  — 
  The 
  strata 
  which 
  follow 
  

   immediately 
  upon 
  the 
  great 
  dislocation 
  form 
  a 
  thick 
  zone 
  of 
  dark 
  

   grey 
  shales 
  (Cba) 
  with 
  a 
  few 
  seams 
  of 
  flagstones. 
  Its 
  lowest 
  beds 
  

   are 
  thick-bedded 
  black 
  mudstones, 
  crowded 
  with 
  Graptolites 
  in 
  an 
  

   excellent 
  state 
  of 
  preservation. 
  The 
  basal 
  beds 
  of 
  the 
  group 
  along 
  

   the 
  line 
  of 
  the 
  fault 
  itself 
  are 
  green 
  flaggy 
  rocks, 
  concretionary 
  and 
  

   more 
  or 
  less 
  calcareous. 
  From 
  these 
  I 
  have 
  procured 
  Pentamerus 
  sp. 
  

   The 
  black 
  mudstones 
  themselves 
  are 
  crowded 
  with 
  Diplograptus 
  tama- 
  

   riscus, 
  Nich., 
  D. 
  modestus, 
  Lapw., 
  Climacograptus 
  normalis, 
  Lapw., 
  

   Monograjjtus 
  tenuis, 
  Portl., 
  M. 
  crenularis, 
  Lapw., 
  M. 
  leptotheca, 
  

   Lapw., 
  together 
  with 
  many 
  fragments 
  of 
  Crustacea 
  and 
  Ortho- 
  

   ceratites. 
  These 
  mudstones 
  graduate 
  upwards 
  into 
  the 
  main 
  mass 
  

   of 
  the 
  grey 
  shales 
  through 
  a 
  small 
  group 
  of 
  striped 
  shales, 
  con- 
  

   taining 
  an 
  abundance 
  of 
  the 
  same 
  fossils 
  with 
  well-preserved 
  Ortho- 
  

   ceratites. 
  

  

  